Wireless communication devices and base station for wireless communication in a wireless communication system

ABSTRACT

The present disclosure is directed to a wireless communication device for wireless communication in a wireless communication system which comprises a base station and a plurality of wireless communication devices arranged in clusters, wherein a unique cluster signature is assigned to each cluster and its wireless communication devices, wherein the wireless communication device is allocated to one of said clusters, and comprises receiving means adapted to receive a unique cluster signature assigned to said one cluster from the base station, storing means adapted to store said received unique cluster signature, and transmission means adapted to transmit said unique cluster signature when the wireless communication device switches into an active state, wherein wireless communication device is adapted to access resources on the basis of resource allocation information received in response to the transmission of said unique cluster signature.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/EP2016/056052, filed on Mar. 18, 2016, the disclosure of which ishereby incorporated by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to wireless communication devices and abase station for wireless communication in a wireless communicationsystem, which comprises a base station and a plurality of wirelesscommunication devices. The disclosure specifically describes a mechanismto detect the resource requests of wireless communication devices andthereafter allocate the radio resources in a wireless network. Thedisclosure can for example and in particular be applied to large scalemachine-to-machine (M2M) communications in a cellular network, includingstationary or low-mobility M2M communications for, e.g. Smart Grid andE-Health applications, as well as high-mobility vehicle-to-vehicle (V2V)communication, but is not limited to these applications.

BACKGROUND

Towards the next generation of mobile and wireless networks,machine-type communications (MTC) is expected to play a significant roleand form the basis for the future Internet of Things (IoT). M2Mcommunications offer a wide range of applications providing variousservices, such as the Smart Grid, the E-health system,Vehicle-to-Vehicle (V2V) communications, and etc. In the rest of thepresent description, all these kinds of wireless communication devices,such as e.g. wireless M2M communication devices are called “devices”.With the rapid growth of the M2M market, the number of devices in awireless communication network can be tremendously increased and canpotentially be very large, thus posing significant challenges to currentradio access networks.

Once a transmission is triggered by a random event, for instance amalfunction in the power network, the device needs certain wirelessresources for its transmission. If a contention-free scheme is applied,a certain amount of dedicated resource blocks will be preserved for thetransmissions, and the devices will access those resources in acoordinated manner. However, these kinds of schemes may lead toexcessive signaling overhead between the devices and inefficient use ofthe reserved resource blocks. Moreover, since the wireless resources arein general very limited, those schemes scale poorly with the increasingamount of devices deployed in the network.

Therefore, for devices which need to access the network randomly, theycan start with sending a resource request to the network in order toindicate their active status and request for the uplink/sidelinkresources for their transmission. A general schematic example of awireless communication network with a base station (BS) 1 and aplurality of wireless communication devices 2 is shown in FIG. 1. In theexample of LTE and LTE-Advance, which is also an example of potentialimplementation of the disclosure, the random access (RA) procedurecomprises four steps as shown in FIG. 2.

Step S1: A device 2 transmits a randomly selected RA preamble sequenceon the Physical Random Access Channel (PRACH) to the base station 1.

Step S2: The base station 1 transmits an RA response on the PhysicalDownlink Shared Channel (PDSCH) in respond to the detected preamblesequence.

Step S3: The device 2 transmits its identity and other messages, e.g., ascheduling request to the base station 1 using the uplink/sidelinkresources assigned in the RA response in the second step S2.

Step S4: The base station 1 echoes the device identity it received inthe third step on PDSCH.

The base station 1 does not necessarily to be the real entity of amacro/micro base station, but also can be any kind of a centralcontroller for resource allocation and network management. All thesefunctional and/or physical entities which perform the relevant functionsare called “base station (BS)” in the rest of the present description ofthe background as well as the various aspects and embodiments of thepresent disclosure.

According to the LTE specifications, each cell is assigned a pool of 64Zadoff-Chu sequences as preambles for the Step S1 transmission. However,a collision will occur if two or more user equipments (UEs), i.e.devices 2, have randomly selected the same preamble. When the number ofaccessing devices 2 becomes excessively large, the simultaneous accessattempts will incur a high probability of collisions in the first stepof the random access, since the number of preambles and the RandomAccess Channel (RACH) resources are quite limited. Hence, the RAprocedure scales poorly with the increasing number of devices 2 in thenetwork and the network will easily become overloaded and congested,leading to high detection failure rate and large access delays.

The massive deployment of devices in the MTC network poses significantchallenges to the current radio network in term of device detection andresource allocation, especially when the devices access the networkrandomly. Seamless coordination and excessive information exchangebetween the devices are required by conventional access schemes tomitigate collisions in the random access channel, which leads toimmoderate signaling overhead.

The object of the present disclosure is therefore to propose amechanism, and specifically wireless communication devices, a basestation and a method for resource allocation for a wirelesscommunication network comprising a plurality of wireless communicationdevices and a base station, in which the signaling overhead for resourceallocation is reduced and a faster and more efficient resource access isprovided.

SUMMARY

This object is solved by a wireless communication device according toclaim 1, a wireless communication device according to claim 7, a basestation according to claim 10, a wireless communication system accordingto claim 15 and a method for resource allocation according to claim 16.Further advantageous features are defined in the respective dependentclaims.

In a first aspect of the disclosure a wireless communication device forwireless communication in a wireless communication system whichcomprises a base station and a plurality of wireless communicationdevices arranged in clusters is provided, wherein a unique clustersignature is assigned to each cluster and its wireless communicationdevices, wherein the wireless communication device is allocated to oneof said clusters and comprises receiving means adapted to receive aunique cluster signature assigned to said one cluster from the basestation, storing means adapted to store said received unique clustersignature, and transmission means adapted to transmit said uniquecluster signature when the wireless communication device switches intoan active state, wherein wireless communication device is adapted toaccess resources on the basis of resource allocation informationreceived in response to the transmission of said unique clustersignature. The unique cluster signature which is transmitted from saidactive wireless communication device can either be transmitted to andreceived by the respective base station and other active wirelesscommunication devices in said one cluster (in the example of afull-duplex case as explained later), or by the respective base stationand one or more head wireless communication device(s) in said onecluster (in the example of a half-duplex case as explained later).

The wireless communication device according to the first aspect asdefined above thus solves the object of the present disclosure in anadvantageous way and provides a reduced signaling overhead for resourceallocation and a faster and more efficient resource access in thewireless communication system. These advantages as well as the furtheradvantages identically apply to the various further aspects of thedisclosure as defined below. Specific advantages are then achieved bythe various implementation forms of the respective aspects of thedisclosure as defined below.

Since the devices in the system are partitioned into clusters, a balk ofrequests from the devices can be handled in a single shot. Since thebehaviors are in general highly correlated among the devices, e.g., dueto proximity, the same service type, and etc. Thus, it is reasonable tocluster the devices according to some of these criteria, where thecorrelation in the device behaviors is exploited for more efficientdevice detection and resource allocation schemes. In addition, since theMTC traffic is characterized by the sporadic communication among a hugenumber of devices, each device has a low probability of being active,thus exhibiting a certain level of sparsity in the device detectionprocess.

The disclosure further uses compressed sensing (CS) techniques, whichare a proper paradigm to deal with high-dimensional signals with asparse representation. It is an emerging signal processing techniquewhere the signal acquisitions are done in a significantly reducedsampling rate, thus the computational complexity is significantlyreduced. Recognizing the large-scale M2M network and the sparsity in theactivation pattern among the devices, the device detection process canbe formulated as a signal recovery procedure of a high-dimensionalsparse signal by the CS principles. Moreover, observing the cluster-likebehavior among the devices, the activation pattern of the devices can beformulated as a particular block sparse signal—with additional in-blockstructure—in CS based applications. Thus the device detection processcan be mapped into the recovery procedure of such a sparse signal.

In order to cope well with the tremendous scaling issues due to massiveconnectivity in large-scale M2M networks and to tackle the excessivesignaling overhead among the devices, distributed schemes are applied tothe present disclosure, where each device determines its resourceallocation autonomously. The distributed schemes call for much lesscoordination and information exchange between the devices, thus thesignaling overhead can be substantially reduced and adapted according tothe size of the network. Therefore, the distributed schemes in generalachieve better scalability with the increasing number of devices in thenetwork, which is an attractive property for large-scale networks.

Therefore, this disclosure suggests a distributed detection scheme ofthe network activation pattern based on CS techniques to facilitateefficient resource allocation strategies for large-scale M2Mcommunications. This disclosure targets to cope with tremendous scalingissues aroused by the MTC network, especially for enhanced devicedetection probability and reduced access delay.

The present disclosure utilizes the framework of compressed sensing fordistributed device detection and resource allocation in large-scale M2Mcommunication networks. The devices deployed in the network arepartitioned into clusters according to some pre-defined criteria. Andthe devices in each of the clusters are assigned a unique clustersignature of a particular design that can be used to indicate theiractive status to the network. By exploiting the sparsity in theactivation pattern of the devices, the device detection problem istackled as a support recovery procedure for a block-sparse signal in theCS based applications. Compared with conventional schemes like LTE RAprocedure and classic cluster-based access approaches, this disclosureachieves better scalability with the network size and sufficientlyreduces the computational complexity as well as the signaling overhead,thus leading to more robust performance in the detection process,especially in terms of higher detection probability and reduced accessdelay.

In a first implementation form of the first aspect the receiving meansis further adapted to receive, together with the unique clustersignature, additional information from the base station, wherein theadditional information includes cluster identification identifying saidcluster, device identification identifying the devices in said clusterand ranking information regarding the resource access ranking of thedevices in said one cluster.

In a second implementation form according to the first implementationform of the first aspect the receiving means is further adapted toreceive said resource allocation information issued in response to thereceived unique cluster signature from said base station, wherein saidresource allocation information comprises information regarding a totalamount of resources allocated for all the active wireless communicationdevices in said one cluster, and further comprising control meansadapted to determine the specific resources to be accessed on the basisof said received resource allocation information and said receivedadditional information.

In a third implementation form according to the second implementationform of the first aspect the receiving means is further adapted toreceive, together with said resource allocation information, the numberof active devices in said cluster and collision patterns from the basestation, and the control means is further adapted to determine saidspecific resources to be accessed on the basis of the received resourceallocation information, the received number of active devices in saidcluster and the received collision patterns as well as said additionalinformation.

In a fourth implementation form according to the third implementationform of the first aspect the receiving means is further adapted tosimultaneously receive unique cluster signatures from other activewireless communication devices in said one cluster, and wherein thecontrol means is adapted to identify other active devices in saidcluster on the basis of the received number of active devices in saidcluster and the received collision patterns as well as the previouslyreceived device identification and unique cluster signatures from otheractive wireless communication devices in said one cluster.

In a fifth implementation form of the first aspect as such or accordingto the first implementation form of the first aspect the receiving meansis further adapted to receive, together with the unique clustersignature, cluster head information from the base station, said clusterhead information identifying a wireless communication device in said onecluster as head communication device, wherein the receiving means isfurther adapted to receive said resource allocation information fromsaid head communication device; wherein the received resource allocationinformation comprises specific information about the resources to beaccessed.

In a second aspect of the disclosure a wireless communication device forwireless communication in a wireless communication system whichcomprises a base station and a plurality of wireless communicationdevices arranged in clusters is provided, wherein a unique clustersignature is assigned to each cluster and its wireless communicationdevices, wherein the wireless communication device is allocated to oneof said clusters as ahead communication device and comprises receivingmeans to receive a unique cluster signature assigned to said one clusterand cluster head information from the base station, said cluster headinformation identifying the wireless communication device in said onecluster as said head communication device, control means adapted togenerate resource allocation information in response to unique clustersignatures received from active wireless communication devices in saidone cluster, and transmitting means adapted to transmit said resourceallocation information to said active wireless communication devices insaid one cluster.

In a first implementation form of the second aspect said receiving meansis further adapted to receive, together with the unique clustersignature, additional information from the base station, wherein theadditional information includes cluster identification identifying saidcluster, device identification identifying the wireless communicationdevices in said one cluster and ranking information regarding theresource access ranking of the wireless communication devices in saidone cluster.

In a second implementation form of the second aspect said receivingmeans is further adapted to simultaneously receive unique clustersignatures from respective active wireless communication devices in saidone cluster, and to receive resource allocation information comprisinginformation regarding the total amount of resources allocated to saidactive wireless communication devices in said one cluster, the number ofactive devices in said cluster and collision patterns from said basestation, wherein the control means is further adapted to identify activewireless communication devices in said one cluster on the basis of thereceived unique cluster signatures, the received number of activedevices in said one cluster and the received collision patterns as wellas the previously received device identification, and to allocatespecific resources to the identified active wireless communicationdevices in said one cluster on the basis of the received resourceallocation information and the previously received ranking informationfrom said base station, and the transmitting means is further adapted totransmit specific resource allocation information regarding the specificallocated resources to the identified active wireless communicationdevices in said one cluster.

In a third aspect of the disclosure a base station for wirelesscommunication in a wireless communication system which comprises thebase station and a plurality of wireless communication devices arrangedin clusters is provided, wherein the base station comprises controlmeans to adapted to generate and allocate a unique cluster signature toeach of the clusters and its respective wireless communication devices,and transmitting means adapted to transmit the generated and allocatedunique cluster signatures to the plurality of wireless communicationdevices.

In a first implementation form of the third aspect the transmittingmeans is further adapted to transmit, together with the unique clustersignature, additional information to the plurality of wirelesscommunication devices, wherein the additional information includescluster identification identifying said clusters, device identificationidentifying the wireless communication devices in said clusters andranking information regarding the resource access ranking of thewireless communication devices in said clusters.

In a second implementation form of the third aspect as such or accordingto the first implementation form of the third aspect the base stationcomprises receiving means adapted to simultaneously receive uniquecluster signatures from respective wireless communication devices,wherein the control means is further adapted to determine, on the basisof the received unique cluster signatures, active clusters, the numberof active devices in each active cluster, and collision patterns withcollision information regarding the interference of the received uniquecluster signatures, and to allocate a total amount of resources for allactive wireless communication devices in each of the active clusters,the transmitting means is further adapted to transmit resourceallocation information regarding the allocated resources, the number ofactive devices in each active cluster and the collision patterns,wherein the resource allocation information comprises informationregarding said total amount of resources for the active wirelesscommunication devices in each of the active clusters.

In a third implementation form of the third aspect the transmittingmeans is adapted to transmit the resource allocation information, thenumber of active devices in each active cluster and the collisionpatterns to the active wireless communication devices in a broadcasttransmission, or the transmitting means is adapted to transmit theresource allocation information, the number of active devices in eachactive cluster and the collision patterns to the active wirelesscommunication devices together with cluster identification identifyingthe active clusters in a multicast transmission.

In a fourth implementation form of the third aspect one wirelesscommunication device in each cluster is allocated as head communicationdevice to said cluster, wherein said transmitting means is furtheradapted to transmit, together with said unique cluster signatures,cluster head information to said one head communication device in eachcluster, and said transmitting means is further adapted to transmit theresource allocation information, the number of active devices in eachactive cluster and the collision patterns to the head communicationdevices in each active cluster.

In a fourth aspect of the disclosure a wireless communication system isprovided comprising a plurality of wireless communication devicesaccording to the first aspect as such or according to one of the firstto fifth implementation forms of the first aspect and a base stationaccording to the third aspect as such or according to one of the firstto fourth implementation forms of the third aspect, or a plurality ofwireless communication devices according to the first aspect as such oraccording to the first or the fifth implementation form of the firstaspect, wireless communication devices according to the second aspect assuch or according to the first or the second implementation form of thesecond aspect and a base station according to the third aspect as suchor according to one of the first to fourth implementation forms of thethird aspect.

In a fifth aspect of the disclosure a method for resource allocation ina wireless communication system which comprises a base station and aplurality of wireless communication devices arranged in clusters isprovided, wherein the base station generates and allocates a uniquecluster signature to each of the clusters and its respective wirelesscommunication devices and transmits the generated and allocated uniquecluster signatures to the plurality of wireless communication devices,and each wireless communication device stores a received unique clustersignature of the cluster to which it is allocated, transmits the uniquecluster signature when the communication device switches into an activestate, receives resource allocation information and accesses resourceson the basis of the received resource allocation information. The uniquecluster signature which is transmitted from said active wirelesscommunication device can either be transmitted to and received by therespective base station and other active wireless communication devicesin said one cluster (in the example of a full-duplex case as explainedlater), or by the respective base station and one or more head wirelesscommunication device(s) in said one cluster (in the example of ahalf-duplex case as explained later).

In a first implementation form of the fifth aspect the receiving stepfurther comprises receiving, together with the unique cluster signature,additional information from the base station, wherein the additionalinformation includes cluster identification identifying said cluster,device identification identifying the devices in said cluster andranking information regarding the resource access ranking of the devicesin said one cluster.

In a second implementation form according to the first implementationform of the fifth aspect the receiving step further comprises receivingsaid resource allocation information issued in response to the receivedunique cluster signature from said base station, wherein said resourceallocation information comprises information regarding a total amount ofresources allocated for all the active wireless communication devices insaid one cluster, and further comprising a control step to determine thespecific resources to be accessed on the basis of said received resourceallocation information and said received additional information.

In a third implementation form according to the second implementationform of the fifth aspect the receiving step further comprises receiving,together with said resource allocation information, the number of activedevices in said cluster and collision patterns from the base station,and the control step further comprises determining said specificresources to be accessed on the basis of the received resourceallocation information, the received number of active devices in saidcluster and the received collision patterns as well as said additionalinformation.

In a fourth implementation form according to the third implementationform of the fifth aspect the receiving step further comprisessimultaneously receiving unique cluster signatures from other activewireless communication devices in said one cluster, and wherein thecontrol step comprises identifying other active devices in said clusteron the basis of the received number of active devices in said clusterand the received collision patterns as well as the previously receiveddevice identification and unique cluster signatures from other activewireless communication devices in said one cluster.

In a fifth implementation form of the fifth aspect as such or accordingto the first implementation form of the fifth aspect the receiving stepfurther comprises receiving, together with the unique cluster signature,cluster head information from the base station, said cluster headinformation identifying a wireless communication device in said onecluster as head communication device, wherein the receiving step furthercomprises receiving said resource allocation information from said headcommunication device; wherein the received resource allocationinformation comprises specific information about the resources to beaccessed.

In a sixth aspect of the disclosure a method for resource allocation ina wireless communication system which comprises a base station and aplurality of wireless communication devices arranged in clusters isprovided, wherein said base station assigns a unique cluster signatureto each cluster and its wireless communication devices, wherein thebases station allocates a wireless communication device to one of saidclusters as a head communication device and wherein the headcommunication device receives a unique cluster signature assigned tosaid one cluster and cluster head information from the base station,said cluster head information identifying the wireless communicationdevice in said one cluster as said head communication device, andperforms a control step to generate resource allocation information inresponse to unique cluster signatures received from active wirelesscommunication devices in said one cluster, and transmits said resourceallocation information to said active wireless communication devices insaid one cluster.

In a first implementation form of the sixth aspect said receiving stepfurther comprises receiving, together with the unique cluster signature,additional information from the base station, wherein the additionalinformation includes cluster identification identifying said cluster,device identification identifying the wireless communication devices insaid one cluster and ranking information regarding the resource accessranking of the wireless communication devices in said one cluster.

In a second implementation form of the sixth aspect said receiving stepfurther comprises simultaneously receiving unique cluster signaturesfrom respective active wireless communication devices in said onecluster, and receiving resource allocation information comprisinginformation regarding the total amount of resources allocated to saidactive wireless communication devices in said one cluster, the number ofactive devices in said cluster and collision patterns from said basestation, wherein the control step further comprises identifying activewireless communication devices in said one cluster on the basis of thereceived unique cluster signatures, the received number of activedevices in said one cluster and the received collision patterns as wellas the previously received device identification, and allocatingspecific resources to the identified active wireless communicationdevices in said one cluster on the basis of the received resourceallocation information and the previously received ranking informationfrom said base station, and the transmitting step further comprisestransmitting specific resource allocation information regarding thespecific allocated resources to the identified active wirelesscommunication devices in said one cluster.

In a seventh aspect of the disclosure a method for resource allocationin a wireless communication system which comprises the base station anda plurality of wireless communication devices arranged in clusters isprovided, wherein the base station performs a control step to generateand allocate a unique cluster signature to each of the clusters and itsrespective wireless communication devices, and transmits the generatedand allocated unique cluster signatures to the plurality of wirelesscommunication devices.

In a first implementation form of the seventh aspect the transmittingstep further comprises transmitting, together with the unique clustersignature, additional information to the plurality of wirelesscommunication devices, wherein the additional information includescluster identification identifying said clusters, device identificationidentifying the wireless communication devices in said clusters andranking information regarding the resource access ranking of thewireless communication devices in said clusters.

In a second implementation form of the seventh aspect as such oraccording to the first implementation form of the seventh aspect thebase station simultaneously receives unique cluster signatures fromrespective wireless communication devices, wherein the control stepfurther comprises determining, on the basis of the received uniquecluster signatures, active clusters, the number of active devices ineach active cluster, and collision patterns with collision informationregarding the interference of the received unique cluster signatures,and allocating a total amount of resources for all active wirelesscommunication devices in each of the active clusters, the transmittingstep further comprises transmitting resource allocation informationregarding the allocated resources, the number of active devices in eachactive cluster and the collision patterns, wherein the resourceallocation information comprises information regarding said total amountof resources for the active wireless communication devices in each ofthe active clusters.

In a third implementation form of the seventh aspect the transmittingstep comprises transmitting the resource allocation information, thenumber of active devices in each active cluster and the collisionpatterns to the active wireless communication devices in a broadcasttransmission, or the transmitting step comprises transmitting theresource allocation information, the number of active devices in eachactive cluster and the collision patterns to the active wirelesscommunication devices together with cluster identification identifyingthe active clusters in a multicast transmission.

In a fourth implementation form of the seventh aspect one wirelesscommunication device in each cluster is allocated as head communicationdevice to said cluster, wherein said transmitting step further comprisestransmitting, together with said unique cluster signatures, cluster headinformation to said one head communication device in each cluster, andsaid transmitting step further comprises transmitting the resourceallocation information, the number of active devices in each activecluster and the collision patterns to the head communication devices ineach active cluster.

Generally, it has to be noted that all wireless communication devices,base stations and their respective means, units and functionalities asdefined in the claims as well as in the following embodiments can beimplemented by software or hardware elements or any kind of combinationthereof. Furthermore, the functionalities of the wireless communicationdevices and base stations may be implemented by processors or maycomprise processors. All steps which are performed by the variousentities described in the present description as well as thefunctionalities described to be performed by the various entities areintended to mean that the respective entity is adapted to or configuredto perform the respective functionalities and steps. Even if in thefollowing description of specific embodiments, a specific functionalityor step to be performed by a general entity is not reflected in thedescription of a specific detailed element of the entity which performsthat specific step or functionality, it should be clear for a skilledperson that these methods and functionalities can be implemented inrespect of software or hardware elements, or any kind of combinationthereof.

BRIEF DESCRIPTION OF DRAWINGS

The present disclosure is in the following explained in detail inrelation to embodiments of the disclosure in reference to the encloseddrawings, in which

FIG. 1 shows a schematic example of a wireless communication systemcomprising a base station and a plurality of wireless communicationdevices,

FIG. 2 shows a general example of a random access procedure,

FIG. 3A, FIG. 3B, FIG. 3C, FIG. 3D show schematic examples of scenarioswith different phases performed by the present disclosure,

FIG. 4 shows a flow chart example of various steps performed in variousphases of the present disclosure in a full-duplex case,

FIG. 5 shows a schematic flow charge of various phases performed by thepresent disclosure in a half-duplex case,

FIG. 6 shows a schematic example of a wireless communication device ofthe present disclosure

FIG. 7 shows a schematic example of a head communication deviceaccording to the present disclosure,

FIG. 8 shows a schematic example of a base station according to thepresent disclosure,

FIG. 9 shows a schematic visualization of a scenario for the generationand detection of unique cluster signatures of the present disclosure,and

FIG. 10 shows a schematic example of the structure of a measurementmatrix.

In the Figures identical reference signs are used for identical or atleast functionally equivalent features.

DETAILED DESCRIPTION

As stated above in the summary, the present disclosure is directed to awireless communication system which comprises a base station 10 and aplurality of wireless communication devices 11 which are arranged inclusters C1, C2 and C3. A schematic example is shown in FIG. 3A. FIGS.3B, 3C and 3D show further scenarios of the various communication andprocessing phases performed by the base station 10 and the wirelesscommunication devices 11 according to the present disclosure. A wirelesscommunication device 11 of the present disclosure is defined accordingto the first aspect and its various implementation forms as definedabove. A base station 10 according to the present disclosure is definedin the third aspect and its implementation forms as defined above. Theoptional example of a wireless communication device 12 designated as ahead communication device is defined in the second aspect and itsimplementation forms as defined above. Such a head communication devicecould be a wireless communication device 11 with its respectivelydefined functionalities and comprise the additional functionalities ofthe head communication device as described, or the head communicationdevice could be a wireless communication device which only comprises andperforms the head communication device functionalities as described.

It has to be further understood that the base station 10 according tothe present disclosure comprises the functionalities of a base station 1as explained in the background part. Similarly, the wirelesscommunication devices 11 of the present disclosure comprise thefunctionalities of wireless communication devices 2 as described in thebackground part. Also, the flow chart of the random access procedureshown in FIG. 2 is identically applicable and implemented into the basestation 10 and the wireless communication devices 11 of the presentdisclosure. Consequently, the schematic block diagram of the wirelesscommunication device 11 according to the present disclosure as shown inFIG. 6, the schematic block diagram of a head communication device 12 ofthe present disclosure, shown in FIG. 7 and the schematic block diagramof a base station 10 of the present disclosure as shown in FIG. 8 onlyshow and describe functionalities which are relevant for implementingthe functionalities according to the present disclosure. Additionalfunctionalities which need to be present in order to unable thecorresponding communication and processing in the respective wirelesscommunication system apart of the common knowledge of the skilled personand are not specifically described. Thus, the wireless communicationdevice 11 is shown in FIG. 6 comprises an antenna 61 to receive andtransmit signals in the wireless communication system, as well asreceiving means 62 and transmitting means 63 respectively adapted toperform the necessary receiving and transmitting functionalities incooperation with the antenna 61. The general processing and controllingfunctions are performed in a control means 64 which is connected to thereceiving means 62 and the transmitting means 63. Further, a storagemeans 65 is connected to the control means 64 in order to store thenecessary information and signals. Similarly, the head communicationdevice 12 is shown in FIG. 7 comprises an antenna 71 to transmit andreceive signals and a wireless communication system, as well asreceiving means 72 and transmitting means 73 for respectively performingreceiving and transmitting functionalities in cooperation with theantenna 71. Further, a control means 74 which is connected to a storagemeans 75 is provided, wherein the control means 74 is adapted to performthe necessary processing functionalities is described in more detailbelow, and is connected to the receiving means 72 and the transmittingmeans 73. The base station 10 shown in FIG. 8 comprises an antenna 81for transmitting and receiving signals in the wireless communicationsystem, which is connected to a receiving means 82 and a transmittingmeans 83 adapted to respectively perform the required receiving andtransmitting functionalities in cooperation with the antenna 81. Acontrol means 84 is adapted to perform the necessary processingfunctionalities in cooperation with a storage means 85 adapted to storethe required signals and information. The control means 84 is generallyconnected to the receiving means 82 and the transmitting means 83.Generally, the receiving means 62, 72, 82 of the wireless communicationdevice 11, the head communication device 12 and the base station 10 areadapted to perform the respectively described and defined receivingfunctionalities. The transmitting means 63, 73, 83 of the wirelesscommunication device 11, the head communication device 12 and the basestation 10 are adapted to perform the respectively described and definedtransmitting functionalities. The control means 64, 74, 84 of thewireless communication device 11, head communication device 12 and basestation 10 are adapted to perform all described processing, controlling,generating, allocating and so forth functionalities described in thepresent description and defined in the various claims for therespectively received information or the respectively to be transmittedinformation. The storage means 65, 75 and 85 respectively store thereceived information or to be transmitted information in cooperationwith the respective control means 64, 74, and 84.

According to the disclosure, the devices 11 are partitioned intoclusters C1, C2, C3, thus a balk of similar requests can be handled in asingle shot. Since the devices 11 in general exhibit highly correlatedbehaviors, e.g., due to proximity, the same service type, and etc., itis reasonable to cluster the devices 11 according to some of thesecriteria. And a device 11 can be assorted into multiple clusters C1, C2,C3 on different features. For example, a temperature sensor in abuilding can be clustered for the building temperature management, butcan also be a member in the fire alarm system. The cluster structuresare known both at the BS 10 and at the devices 11 during the deviceregistration process to the network and updated periodically.

Moreover, since the MTC traffic is characterized by the sporadiccommunication among a huge number of devices 11, each device 11 has alow probability of being active, thus exhibiting a certain level ofsparsity in the detection activity.

For example in an E-health system a patient has multiple measurementdevices 11 attached to his/her body to keep track of his/her healthconditions. These devices 11 include sensors measuring the bodytemperature, blood pressure, heart rate and etc. Therefore, it isreasonable to assort these devices 11 into the same cluster C1 or C2 orC3. However, at a certain time instant, only a small number of patientsobserve abnormal symptoms in the hospital. In this case, severalsensors, i.e. devices 11 attached to the patient become triggered andstart accessing the network to report their status, such as the heartrate sensor and the blood pressure sensor. A cluster C1, C2, C3 iscalled “active” if one or more devices 11 from the cluster are active.Therefore, in general at a certain time instant, only several clustersbecome active and only a small number of the devices 11 in those activeclusters are triggered to report to the network. Thus, a twofoldsparsity pattern, namely the block sparsity and in-block sparsity, canbe defined to model the active status of the devices 11. Hereby, BlockSparsity means that only several of the clusters C1, C2 or C3 becomeactive at a certain time instant, and In-block Sparsity means that onlyseveral devices from the same cluster C1, C2 or C3 are active.

In addition, both the BS 10 and each device 11 in the network also hasthe (estimated) channel information from other devices 11 to itself,which is required in the algorithms for device detection of thedisclosure. The channel information can be obtained via statisticalchannel knowledge, location-based estimation or long-term observation,and will be stored in the storage means 75 of each device 11 and in thestorage means 85 of the BS 10.

In addition, a ranking among the devices 11 in each cluster C1, C2, C3is conducted in advance in order to determine the order for the activedevices to access the assigned resource blocks by the BS 10. As aresult, the active devices access the corresponding resources accordingto their ranking in the cluster. For instance, 2 resource blocks areassigned to a particular cluster C1, C2, C3 where 2 devices 11 in thecluster C1, C2 or C3 are active. Then the active device with a higherranking will access the first resource block for transmission and thedevice with a lower ranking will take the second resource block. Thedevices 11 can be ranked according to some pre-defined rule, e.g., theorder of the device identification ID, service priority, and etc. Andthe ranking information is also informed to the devices in advance bythe BS 10, and will be stored in the storage means 75 of each device 11.

In this disclosure, the devices 11 in each of the clusters C1, C2, C3are assigned a unique cluster signature, which is also called uniquecompressed signature or simply signature in the present description andused to indicate their active status to the network, the design of whichis different from the preambles (Zadoff-Chu sequences) in the LTE RAprocedure and will be introduced in detail in below in the section“Signature Design”, i.e. is unique for this cluster in the network(system). Each of the compressed signatures indicates the membership toa particular cluster, and is informed to the devices 11 in thecorresponding cluster C1, C2, C3 during the device registration phase aswell, and will be stored in the storage means 75 of each device 11.Furthermore, the particular design of the compressed signatures can alsoindicate other properties of the cluster if needed, such as the amountof resource blocks requested by each device 11 in the cluster.

A full-duplex system allows data to be transmitted in both communicationdirections at the same time, which means the signals can be transmittedand received simultaneously, while half-duplex systems only allowcommunication in a single direction at a time. Usually the terms“full-duplex” and “half-duplex” are used to describe point-to-pointsystems, but in this description they are extended to multi-pointsystems composed of multiple connected entities or devices thatcommunicate with each other. Therefore in this work, “full-duplex” meansa device 11 or BS 10 can both transmit and receive data on the wirelesschannel simultaneously. Depending on the network configuration whetherthe full-duplex mode is supported by the devices or not, the proposedscheme for the distributed device detection and resource allocation isdifferentiates in two cases.

If the full-duplex mode is supported, the proposed scheme mainlyconsists of four phases, which are schematically illustrated in FIGS.3A, 3B, 3C and 3D and in the flow chart of FIG. 4 (full-duplex case).

FIG. 3A: Phase 1 (Clustering): As the devices 11 are partitioned intoclusters C1, C2, C3 and the devices 11 in each cluster C1, C2, C3 arerespectively designed to obtain a unique compressed signature (i.e. aunique cluster signature), all these relevant information is informed tothe devices 11 and updated periodically by the BS 10. The informationincludes the cluster identifications, the device identificationsidentifying the devices in each cluster, the ranking informationregarding the resource access ranking of the devices, and the compressedsignatures, respectively distributed to each of the clusters (Step S41).There is only a single compressed signature in each cluster C1, C2, C3and only this unique signature is issued to all devices 11 in therespective cluster C1, C2, C3.

FIG. 3B: Phase 2 (Signal Acquisition): Once devices switch into anactive state and start accessing to the network, they transmitsimultaneously the compressed signatures to the respective BS10 and theother active devices 11 in the same cluster (full-duplex) or to therespective BS 10 and a head communication device 12 (half duplex) toindicate their active status to the network. With full-duplextransceivers, all the devices 11 and the BS10 receive individual linearcombinations of the transmitted signatures.

FIG. 3C: Phase 3 (Decoding at BS 10): The BS10 detects the activeclusters, the number of active devices of each cluster C1, C2, C3, aswell as the collision patterns with collision information regarding theinterference of the received compressed signatures. Then it broadcaststhis information to the devices 11 and assigns a certain amount ofresources to each of the active clusters accordingly (Step S43). Theinformation can also be multicast by the BS 10 to the active devices inthose detected active clusters by indicating the detected cluster IDs.

FIG. 3D: Phase 4 (Decoding at Devices): Each active device performsdevice detection for its corresponding cluster C1, C2, C3 using itsreceived compressed signatures and the broadcast information from the BS10 in Phase 3. Then it detects its ranking among all the active devicesin the cluster and accesses the corresponding resource assigned by theBS 10 for transmission (Step S44).

For illustration, it is assumed that 100 devices 11 are deployed in thenetwork i.e. the wireless communication system, indexed from 1 to 100.Then every 10 of them are partitioned into a cluster C1, C2, C3, whichformulates 10 clusters of size 10. And the devices 11 in each clusterC1, C2, C3 are ranked according to the order of their index. And theunique compressed signatures used by the devices 11 in each cluster C1,C2, C3 are notified by the BS10 during the initial device registrationto the network. At a certain time instant, for example, device 4 and 9from cluster C1 and device 26 and 29 from cluster C3 are triggered andbecome active. Then they start transmitting their compressed signaturesto indicate their active status, and each device requests one resourceblock for transmission. With full-duplex transceivers, both the BS 10and the devices receive linear combinations of the transmittedcompressed signatures by the active devices (Step S42). Then the BS10 isable to detect cluster C1 and C3 as the active clusters, with eachhaving 2 active devices. Then this information is broadcasted to theactive devices in cluster C1 and C3 and assigns 2 resource blocks forcluster C1 and C3 respectively (Step S43). Upon receiving the broadcastmessages, the active devices perform device detection using their ownreceived compressed signatures (Step S44). For example, device 4 incluster C1 detects that both device 9 and itself are active in itscluster. Since it has a higher rank as its index is smaller, it accessthe first resource block assigned by the BS 10 to cluster C1 fortransmission, while device 9 takes the second one. The same approachalso applies for device 26 and 29. In this way, the BS 10 assigns acertain amount of resource blocks to the detected active clusters basedon the detected number of active devices in each cluster, and the activedevices access the corresponding resources based on the device detectionof their own clusters.

However, if full-duplex operations are not supported by the devices 11,and the half-duplex case applies, then a cluster head i.e. a headcommunication device 12 is defined, in advance for each of the clustersC1, C2, C3. The cluster heads are selected with the property not totransmit concurrently with the other devices in the same cluster.Alternatively, if one of the devices 11 in the cluster C1, C2, C3supports full-duplex transmissions, it can be assigned as the clusterhead 12 for its cluster C1, C2, C3. The cluster heads are supposed toknow the cluster structures as well as the estimated channel informationfrom the cluster members to themselves.

To this end, the proposed scheme under the non-full-duplex (i.e. halfduplex) assumption performs the procedure as follows (and as shown inFIG. 5). At first the cluster information including the cluster headidentifications and the information mentioned in Phase 1 under thefull-duplex assumption is informed to the devices 11 and the clusterheads 12 by the BS 10 during the device registration (Step S51 a, S51b). Thereafter in the signal acquisition phase, after the active devicestransmit their individual signatures to indicate their active status,the cluster heads 12 collect their own measurements, which are thelinear combinations of the transmitted signatures (Step 52 a, 52 b).Decoding procedure at the BS side is same as Phase 3 under thefull-duplex assumption (Step S53). Afterwards, the cluster heads of theactive clusters perform device detection for their correspondingclusters C1, C2, C3 and detect the ranking of the active devices intheir clusters using the same decoding algorithms as proposed for Phase4 under the full-duplex assumption. Then the cluster head 12 broadcasts,multicasts or unicasts the decoded ranking information of the activedevices to the rest of active devices in the cluster (Step 54), andthose active devices access the corresponding resources for transmissionbased on their ranking afterwards.

Optionally, each cluster C1, C2, C3 could have multiple cluster heads 12and all the devices 11 can be regarded as cluster heads for theircorresponding clusters. Then they perform all the decoding procedure asdescribed above. Only the non-active device which has a predefinedhighest ranking in the cluster broadcasts its decoded information to therest of the devices in its cluster in the last step (Step 54).

In the next sections, details about the proposed algorithms forsignature design (i.e. design of the unique cluster signatures), and thedecoding procedure at the BS and at the devices, respectively aredescribed.

Consider an M2M network with N devices, which are partitioned in advanceinto L clusters of equal sized according to some pre-defined criteria(N, L and d are natural numbers). As defined previously, the twofoldsparsity among the devices, namely the block sparsity and in-blocksparsity, are K_(B) and K_(I), respectively. That is, only K_(B) out ofL clusters are active, and the number of active devices in each clusteris at most K_(I). In addition, S_(B) is denoted as the block support,which is defined to be the set of index of the active clusters.Similarly, S_(I,l)is denoted as the in-block support, indicating the setof indices of the active devices in cluster 1. Since the activationpattern of the devices is K_(B) block sparse and K_(I) in-block sparse,we have the cardinality of the sets |S_(B)|=K_(B) and |S_(I,l)≤K_(I) forall the clusters C1, C2, C3.

Therefore, the total number of active devices in the network isK≤K_(B)K_(I). Due to the sparse nature of the event occurrence in MTC,K<<N. Herein, a K-sparse binary sequence x of length N to model theactivation pattern of the devices 11, with entry “1” indicating thecorresponding device to be active and “0” otherwise. Furthermore, x_(l),l ε{1, . . . , L} is denoted as the status vector for cluster l. Thus,the activation pattern of the devices is formulated as a particularblock sparse signal—with additional in-block structure—in the CS basedapplications.

The CS related techniques are applied in the proposed distributed devicedetection and resource allocation scheme to reconstruct the K-sparsevector x. The transmission scenario and the target problem can bemodeled into a CS based application as illustrated in FIG. 9, where thedetailed algorithms will be introduced in the Sections. “Block SupportRecovery at BS” and “In-block Support Recovery at Devices.”

First, each of the active devices transmits a specially designedcompressed signature to the network to indicate its active status, whichcorresponds to a certain column of the measurement matrix A in the CStheory. The compressed signatures transmitted by the active devices getsuperimposed in the wireless channel, and both the BS 10 and the devicescollect a linear combination of the transmitted signatures. First, theBS 10 detects the active clusters S_(B) as well as the number of activedevices in each cluster |S_(I,l)|. Then it broadcasts this informationto the devices and assigns a certain amount of resources to the detectedclusters accordingly. Afterwards, the active devices use the broadcastinformation by the BS and their own received compressed signatures toperform the device detection in a distributed manner, and the activationpattern x of the devices can be eventually recovered using the proposedscheme. Then each of the active devices has knowledge of all the activedevices S_(I,l) in its cluster and accesses the corresponding assignedresource block based on its ranking in the cluster.

Herein, the object of interest is to perform block support recovery atthe BS and the in-block support recovery at the device side. To bespecific, the goal is to obtain an accurate estimate of S_(B) and|S_(I,l)| for all the clusters at the BS, and thereafter, an accurateestimate of S_(I,l) at the device side for each of the clusters.

Signature Design

The CS theory is applied to the transmissions incurred by the devices 11in the network. To this end, the measurement matrix A of size M×N isintroduced, each column of which, say column i denoted by α_(i),corresponds to the compressed signature sent by the i-th device if it isactive. Denoted by Γ(R, T, L, d, α) is a particular distribution overmatrices having RT rows and Ld columns, and the measurement matrix A isa structured random matrix drawn from this distribution, i.e., A˜Γ(R, T,L, d, α).

As illustrated in FIG. 10, the measurement matrix A is composed of thevertical concatenation of T individual random matrices, denoted as A_(t)for t ε{1, . . . , T}. Meanwhile, each A_(t) consists the horizontalconcatenation of L sub-matrices A_(t,l) for l ε{1, . . . , L} . EachA_(t,l) a sparse matrix containing exactly d non-zero components—locatedon the same row and with the same value. The index of the row withnon-zero elements is chosen uniformly at random from the set {1, . . . ,R}, and the non-zero component takes the value of ⊥α with probability ½.

For a given realization of A_(t,l), let h_(t,l) ε{1, . . . R} denote theindex of the row of A_(t,l) with non-zero entries, and s_(t,l) ε{−α, +α}be the corresponding value of the non-zero components in A_(t,l).

To this end, each of the compressed signatures transmitted by thedevices, which is the corresponding column of the structured measurementmatrix A, is a sparse sequence of length M with sparsity level T.

Block Support Recovery at BS 10

As mentioned previously, the decoding procedure at the BS side aims todetect the number of active clusters and the number of active devices ineach cluster, which is to obtain an accurate estimation of the blocksupport S_(B) and the cardinality of the in-block support |S_(I,l)| forall the active clusters.

Denote H_(B) as the channel matrix between the devices and the BS, and ζas the thermal noise vector. Then the signal/measurements y received bythe BS at some given time instant is given by

y=AHBx+ζ  (1)

For illustration, suppose that the measurements are collected withnoise-free transmissions y=AHBx. Since the channel knowledge H_(B) isassumed to be known at the devices, we take, for instance, the pseudoinverse of the channel matrix H_(B) ⁺ at the transmitter side. Then theobtained measurements at the BS are given as

y=AHBHB+x=Ax   (2)

The Count-Sketch procedure is extended to realize the decoding processat the BS, which is implemented as follows.

Denote y_(t) as the subvector of y corresponding to measurementsobtained via the submatrix A_(t), i.e, y_(t)=A_(t)x, for t ε{1, . . . ,T}. For each t, the signal estimates {tilde over (x)}_(t) are formed byindexing and scaling the entries of the corresponding observationsy_(t), which is formulated as {tilde over (x)}_(t)=A_(t) ^(T)y_(t).Recall that each A_(t) consists the horizontal concatenation of Lsub-matrices A_(t,l), which are sparse matrices containing d non-zerocomponents located on the same row h_(t,l) and with the same values_(t,l). Then the individual entries of {tilde over (x)}_(t) are givenas {tilde over (x)}_(t,i)=s_(t,l)y_(t,h) _(t,l) for i ε {1, . . . , N}if device i belongs to the l-th cluster. Thereafter, a signal estimate{circumflex over (x)}_(i) is formed whose entries are given

{circumflex over (x)} _(i)=median{{circumflex over (x)}_(t,i)}_(t=1)^(T), for iε{1, . . . N}  (3)

In other words, each entry of the signal estimate is obtained as themedian of the corresponding entries of the estimate {tilde over(x)}_(t). Similarly, the block-wise estimate x _(t) can be obtained as

x _(t)=median{{circumflex over (x)}_(i)}_(i=dl−d+1) ^(dl), for lε{1, . .. L}  (4)

For a given x_(t) from cluster l ε SB, the estimate {tilde over(x)}_(t,i) corresponds exactly to the signals from cluster l wheneverh_(t,l) is distinct from h_(t,l) , for all l εS_(B)\l. Conditioned onthis,

{tilde over (x)} _(t,i) =s _(t,l) y _(t,h) _(t,l) =s _(t,l)(Σ_(i=1) ^(d)s _(t,l) x _(i))=s _(t,l) ²(Σ_(i=1) ^(d) x _(i))=α²|S_(I,l)|  (5)

where the second step follows from the structure of A_(t,l) with equalnon-zero elements on the same row, and the last step follows since x_(i)ε{0, 1} is drawn from a binary ensemble.

By taking the median value block-wisely among all individual estimationsas in (4), each of the estimates x _(l) from the l-th clustercorresponds to |S_(I,l)|—the ultimate goal for block support recovery atthe BS. Furthermore, the size of the in-block support set |S_(I,l)| canbe obtained as

$\begin{matrix}{{{S_{I,l}} = \left\lbrack {\frac{1}{\alpha^{2}}{\overset{\_}{x}}_{l}} \right\rbrack},{{{for}\mspace{14mu} l} \in \left\{ {1,\ldots \mspace{14mu},L} \right\}}} & (6)\end{matrix}$

Therefore, since |S_(I,l)| indicates the number of active devices incluster l, those clusters with |S_(I,l)|>0 are marked as “active” anddetected by the BS 10. Besides, if an individual estimate {circumflexover (x)}_(i) is much larger than the block-wise estimate x _(l), i.e.,{circumflex over (x)}_(i)>>x _(l), it indicates the correspondingmeasurement with index i suffers strong interference from the otherclusters. Thus we mark the measurement as “collided” and keep its indexin the collision pattern for the corresponding cluster.

Furthermore, with block sparsity K_(B), the probability of theconditions for (5) to hold is calculated as

$\begin{matrix}{{P\left( {{\overset{\sim}{x}}_{t,i} = {\alpha^{2}{S_{I,l}}}} \right)} \geq \frac{R - K_{B} - 1}{R}} & (7)\end{matrix}$

By applying the union bound over all the clusters to ensure theconditions for (5), it leads to a requirement of R=O(K_(B)) and T=O(logL) to guarantee the reliable block recovery at the BS with overwhelmingprobability.

After the BS 10 detects the active clusters in the network, the numberof active devices in each active cluster (without knowing exactly whichone), and the collision patterns in the measurements, it broadcasts thisinformation to the devices and assigns a certain amount of resources tothe active clusters accordingly.

In-Block Support Recovery at Devices

During the acquisition phase, either the active devices or the clusterheads also collect their own measurements, which are linear combinationsof the compressed signatures transmitted by the active devices. Asmentioned previously, with the collected measurements and the broadcastmessages by the BS 10 as side information, the devices perform in-blocksupport recovery to detect their order of index among the active devicesin the corresponding clusters.

Taking the measurement matrix A for the signature design in Section 7.1and again assuming noise-free transmissions, the measurements collectedat the device side are given by

y _(D) =AH _(I) H _(B) ⁺ x=Ãx   (8)

where HI is an N×N matrix representing the wireless channels between thedevices.

According to the specific structure of the measurement matrix A, an M×dsub-matrix A_(l) of A is denoted as the set of signatures utilized bythe devices from the l-th cluster. Thence, A_(l) has only T rows withnon-zero components, whose index are denoted by the set Di. Thus, inorder to perform the in-block support recovery, one needs to focus ony_(D,l)—a vector composed of the entries of y_(D) corresponding toD_(l). Ã_(D,l) is denoted as a T×d sub-matrix of Ã with verticalconcatenation of rows corresponding to D_(l) and columns for cluster l.Therefore,

y_(D,l)=Ã_(D,l)x_(l)   (9)

With the randomness in Ã_(D,l) introduced by the wireless channelsbetween the devices, some standard greedy algorithms can be used such asOrthogonal Matching Pursuit, OMP, or Iterative Hard Thresholding, IHT,to perform the in-block support recovery.

Moreover, the algorithm can be further optimised by exploiting thefeedback information from the BS 10 on the number of active devices|S_(I,l)| in the cluster and the collision patterns in the collectedmeasurements. On one hand, those collided measurements detected by theBS, which suffer strong interference from the other clusters, can bediscarded for more reliable processing. And on the other hand, thenumber of iterations needed for implementing the greedy algorithms canbe limited to |S_(I,l)| since the cardinality of the support is alreadyknown, thus leading to significantly reduced computational complexity.The detailed algorithm is summarized in Table 1.

TABLE 1 Extended greedy algorithm for in-block support recoveryAlgorithm 1 Extended OMP for In-block Support Recovery Input: A₁, y_(l),|S_(I,l)|, and the collision pattern for block l. Output: S_(I,l).  1.Discard the collided measurements in y_(l) and the corresponding rows inA_(l) according to the collision pattern. Denote the remainingmeasurements as {tilde over (y)}_(l) and the measurement matrix asÃ_(l).  2. Initialize the residual r₀ = {tilde over (y)}_(l), the indexset Λ₀ = ∅, the matrix of the chosen atoms Φ₀ = ∅, and the iterationcounter t = 1.  3. Choose the column of Ã_(l) with index λ_(t) that isbest matched to r_(t−1) according to${{{\lambda_{t} = {\arg \underset{a_{\lambda} \in {\overset{\sim}{A}}_{l}}{\; \max}}}} < r_{t - 1}},{a_{\lambda} > {_{2}.}}$ 4. Augment the index set Λ_(t) = Λ_(t−1) ∪{λ_(t)} and the matrix of thechosen atoms Φ_(t) = [Φ_(t−1) a_(λ) _(t) ].  5. Solve the least squareerror minimization problem to obtain a new signal estimate:$x_{l,t} = {\arg {\; \;}{\min\limits_{x_{l}}{{{y_{l} - {\Phi_{t}x_{l}}}}_{2}.}}}$ 6. Update the residual as r_(t) = {tilde over (y)}_(l) − Φ_(t)x_(l,t). 7. Increment t by 1, and return to Step 2 until t > |S_(I,l)|.  8.Return S_(I,l) = Λ_(t).

It has been proven that for a certain random measurement matrix, aK-sparse signal can be reliably reconstructed with the CS methods if thenumber of measurements M≥cK log N, where c is a constant. For thepresent specific problem, since the signal of interest is of dimension dand with sparsity level K_(I), the in-block support can be decoded withhigh probability if the number of effective measurements satisfies

T=cK _(I)log d=O(K _(I) log d)   (10)

The method described in this disclosure is investigated for distributeddevice detection and resource allocation in large-scale M2Mcommunication networks. The described method can be widely applied toall kinds of existing M2M devices, without special requirements andlimitation on the mobility type, computational capabilities, and etc.

This disclosure utilizes the framework of compressed sensing fordistributed detection of the network activation pattern to facilitateefficient resource allocation in the MTC networks, which exploits thecorrelation in the device behaviors and the sparsity in the activationpattern of the devices. By applying the distributed schemes and theoptimization in the algorithms, this disclosure achieves betterscalability with the network size and sufficiently reduces thecomputational complexity, thus leading to more robust performance in thedetection process, especially in terms of higher detection probabilityand reduced access delay.

A preliminary evaluation using the described method was made by theinventors. In the experiment, the number of devices in the network wastaken to be N=10000 and they were partitioned into L=100 clusters withequal size d=100. The sparsity level K=K_(B)K_(I) was set within therange between 10 and 100. Comparisons were made between the proposedscheme and two classical access schemes, namely the LTE random accessprocedure and the conventional cluster-based approach where a clusterhead aggregates messages/requests for the rest of the devices in thecluster.

It was observed that the scheme of the disclosure significantlyoutperformed the classical approaches both in terms of detectionprobability and access delay, thus showing much more reliableperformance against the increasing number of devices deployed in thenetwork.

The disclosure is not limited to the specific examples and especiallynot the communication standard LTE. The disclosure discussed above canbe applied to any suitable wireless communication standard and wirelesscommunication system with a base station or and a number of wirelesscommunication devices.

The disclosure has been described in conjunction with variousembodiments herein. However, other variations to the disclosedembodiments can be understood and effected by those skilled in the artin practicing the claimed disclosure, from a study of the drawings, thedisclosure and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps and the indefinite article“a” or “an” does not exclude a plurality. A single processor or otherunit may fulfill the functions of several items recited in the claims.

The mere fact that certain measures are recited in usually differentdependent claims does not indicate that a combination of these measurescannot be used to advantage. A computer program may bestored/distributed on a suitable medium, such as an optical storagemedium or a solid-state medium supplied together with or as part ofother hardware, but may also be distributed in other forms, such as viathe internet or other wired or wireless communication systems.

1. A first wireless communication device for wireless communication in awireless communication system, wherein said wireless communicationsystem comprises a base station and a plurality of wirelesscommunication devices arranged in clusters, wherein a different clustersignature is assigned to each cluster and one or more wirelesscommunication devices in the cluster, wherein the first wirelesscommunication device is allocated to a first cluster, the first wirelesscommunication device comprising: a receiver, configured to receive afirst cluster signature assigned to said first cluster from the basestation, a memory, configured to store said first cluster signaturereceived from the base station, and a transmitter, configured totransmit said first cluster signature in response to the wirelesscommunication device switching into an active state, wherein the firstwireless communication device is adapted to access resources based onresource allocation information received in response to the transmittertransmitting said first cluster signature.
 2. The first wirelesscommunication device according to claim 1, wherein the receiver isfurther configured to receive additional information from the basestation, wherein the additional information includes clusteridentification information identifying said first cluster, deviceidentification information identifying or more wireless communicationdevices in said first cluster, and ranking information regardingresource access ranking of the one or more wireless communicationdevices in said first cluster.
 3. The first wireless communicationdevice according to claim 2, wherein the receiver is further configuredto receive said resource allocation information from said base station,wherein said resource allocation information comprises informationregarding a total amount of resources allocated for active wirelesscommunication devices in said first cluster, the first wirelesscommunication device further comprising: a processor configured todetermine the resources to be accessed by the first wirelesscommunication device based on said resource allocation information andsaid additional information.
 4. The first wireless communication deviceaccording to claim 3, wherein the receiver is further configured toreceive a number of active wireless communication devices in said firstcluster and collision patterns from the base station, and wherein theprocessor is further adapted to determine said resources to be accessedby the first wireless communication device based on the resourceallocation information, the number of active wireless communicationdevices in said first cluster, said collision patterns, and saidadditional information.
 5. The first wireless communication deviceaccording to claim 4, wherein the receiver is further configured toreceive cluster signatures from other active wireless communicationdevices in said first cluster, and wherein the processor is adapted toidentify the other active devices in said first cluster based on thenumber of active wireless communication devices in said first cluster,the collision patterns, the device identification information, and thecluster signatures received from the other active wireless communicationdevices in said first cluster.
 6. The first wireless communicationdevice according to claim 1, wherein the receiver is further configuredto: receive cluster head information from the base station, said clusterhead information identifying a wireless communication device in saidfirst cluster as a head communication device, and receive said resourceallocation information from said head communication device, wherein theresource allocation information comprises information about theresources to be accessed hy the first wireless communication device. 7.A first wireless communication device for wireless communication in awireless communication system, wherein the wireless communication systemcomprises a base station and a plurality of wireless communicationdevices arranged in clusters, wherein a different cluster signature isassigned to each cluster and one or more wireless communication devicesin the cluster, wherein the first wireless communication device isallocated to a first cluster as ahead communication device, the firstwireless communication device comprising: a receiver, configured toreceive a first cluster signature assigned to said first cluster andcluster head information from the base station, said cluster headinformation identifying the first wireless communication device in saidfirst cluster as said head communication device, a processor, configuredto generate resource allocation information in response to clustersignatures received from active wireless communication devices in saidfirst cluster, and a transmitter, configured to transmit said resourceallocation information to said active wireless communication devices insaid first cluster.
 8. The first wireless communication device accordingto claim 7, wherein said receiver is further configured to receiveadditional information from the base station, wherein the additionalinformation includes cluster identification information identifying saidfirst cluster, device identification information identifying one or morewireless communication devices in said first cluster, and rankinginformation regarding resource access ranking of the one or morewireless communication devices in said first cluster.
 9. The firstwireless communication device according to claim 8, wherein saidreceiver is further configured to: receive cluster signatures from saidactive wireless communication devices in said first cluster, receiveinformation regarding a total amount of resources allocated to saidactive wireless communication devices in said first cluster, and receivea number of active wireless communication devices in said first clusterand collision patterns from said base station; wherein the processor isfurther configured to: identify the active wireless communicationdevices in said first cluster based on the cluster signatures, thenumber of active wireless communication devices in said first cluster,the collision patterns,. and the device identification, and allocateresources to the active wireless communication devices in said firstcluster based on the resource allocation information and the rankinginformation from the base station.
 10. A base station for wirelesscommunication in a wireless communication system, wherein the wirelesscommunication system comprises the base station and a plurality ofwireless communication devices arranged in clusters, the base stationcomprising: a processor, configured to generate, for each cluster, arespective cluster signature for the cluster and one or more wirelesscommunication devices in the cluster, and a transmitter, configured totransmit, for each cluster, the respective cluster signature to theplurality of wireless communication devices in the cluster.
 11. The basestation according to claim 10, wherein the transmitter is furtherconfigured to transmit, for each cluster, additional information to theplurality of wireless communication devices in the cluster, wherein theadditional information includes cluster identification informationidentifying the cluster, device identification information identifyingthe plurality of wireless communication devices in the cluster, andranking information regarding resource access ranking of the pluralityof wireless communication devices in the cluster.
 12. The base stationaccording to claim 10, further comprising: a receiver, configured toreceive cluster signatures from wireless communication devices, whereinthe processor is further configured to: determine, based on the clustersignatures, active clusters, a number of active wireless communicationdevices in each active cluster, and collision patterns with collisioninformation regarding interference of the cluster signatures, andallocate a total amount of resources for active wireless communicationdevices in the active clusters, and the transmitter is furtherconfigured to transmit resource allocation information regarding theallocated resources, the number of active wireless communication devicesin each active cluster, and the collision patterns, wherein the resourceallocation information comprises information regarding said total amountof resources for the active wireless communication devices in the activeclusters.
 13. The base station according to claim 12, wherein: thetransmitter is configured to transmit the resource allocationinformation, the number of active wireless communication devices in eachactive cluster, and the collision patterns to the active wirelesscommunication devices in a broadcast transmission, or the transmitter isconfigured to transmit the resource allocation information, the numberof active wireless communication devices in each active cluster, and thecollision patterns to the active wireless communication devices togetherwith cluster identification information in a multicast transmission. 14.The base station according to claim 12, wherein one wirelesscommunication device in each cluster is allocated as a headcommunication device for said cluster, wherein the transmitter isfurther configured to; transmit clustcr signatures, cluster headinformation to said one head communication device in each cluster, andtransmit the resource allocation information, the number of activewireless communication devices in each active cluster, and the collisionpatterns to the head communication devices in each active cluster.
 15. Amethod for resource allocation in a wireless communication system,wherein the wireless communication system comprises a base station and aplurality of wireless communication devices arranged in clusters, themethod comprising: generating, by the base station, a respective clustersignature for the cluster and one or more wireless communication devicesin the cluster; and transmitting, by the base station, the respectivecluster signature to the plurality of wireless communication devices inthe cluster.